Pump or compressor



Nov. A16, 1937. H. L.. BANcRoFT ET Al. 2,099,326

PUMP OR COMPRES SOR Filed Aug. 18, 1.956 2 Sheets-Sheet l ATTORNEYS Nov. 16, 1937. H. l..v BANfiROf-T ET AL 2,099,326

PUMP OR COMPRESSOR Filed Allg. 18, 1956 2 sheets-sheet 2 INV ENTORS Howard L. Banc/*0H- ATTORN EY 5 Patented Nov. 16, 1937 UNITED I STATES 2,099,326 PUMP on' COMPRESSOR Howard L. Bancroft, Sharpsville, Pa.,1and Horace A S.. Smith, Hubbard, Ohio Application August 18, 1936, Serial No. 96,636

8 Claims.

This invention relates to improvements in pumps or compressors, and has reference especially to double-acting devices of'this kind. The unit illustrated herein is intended primarily for small compressors, as for instance compressors employed in domestic refrigerating plants, but

the invention is susceptible of a wide variety of uses, including liquid `pumps and vacuum pumps, and in its broader aspects it has utility as a motor.

One of the objects of ,thev invention is a simplification of devices of this character, principally with respect to the valving of the pump or compressor. Y Another object is to so arrange ports in the valve piece as to cause the paths of the two piston ports to overlap, whereby a Vvalve piece of minimum size for a given piston stroke Vis provided.l Y

Other objects and features of novelty lwill appear as we proceed with the description of that embodiment of the invention which, for the purposesof the present application, we have illustrated Vin the accompanying drawings, vin which Fig. 1 is atop plan view of a compressor embodying the invention. e Y

Fig. 2 is aside view of the same with certain parts shown in central vertical section.

Fig. 3 is a cross section taken substantially on i the line 3--3 of Fig.l 2.

Fig. 4 is an elevational View ofthe outer side of the valve piece.

Fig. 5 is a similar View of the inner side thereof.

Fig. 6 is a View similar to Fig. 2, showing the piston at the opposite end of its stroke.

Fig. 7 is a view similar to Figs. 2 and 6, showing the piston at the middle of its stroke.

Fig. 8 is a View similar to Fig. 2 showing a'modiiication of the invention designed for the pumping of liquid.

Fig. 9 is an elevational vview of the inner side of the valve piece of Fig.` 8, and

Fig. 10 is a view similar to Fig. 9 showing a modified form of valve for liquid pumping.

In the drawings we have illustrated a cylinder I provided with any suitable arrangement and number-of cooling` fins Il. At its ends the cylinderis closed, in this instance by means of head plates t2 provided' with extensions and feet I3 for attachment, tov a base or support. The heads l2 arev attached to the cylinder by screws I4, with gaskets t interposed to seal the joints.

' Midwayl between the ends of the cylinder the casting of which it is constructed is formed with a` cylindrical transverse casing lliL of larger diameter than the cylinder proper, this casing being closed at opposite ends by plates I1 and `I8 that are secured to the casing by screws I9 and 20 respectively, gaskets 2| and 22 being used atthe joints.

Within the cylinder we mount a double ended piston 23, which is preferably of uniform size throughout its` length being freely movable within the cylinder both rotatablyandlongitudinally. Piston rings 24 may be provided near the ends of the piston. Plate I8 has a central boss25 in which is formed a bearing for a shaft 26 that may be driven by an electric motor or other suitable source of power. The inner extremity of shaft 26 merges with or has secured thereto a crank plate 21. 28 is an inwardly extending eccentric boss on plate 21. This boss and theplate 21' are bored to provide a cylindrical bearing, for a ball 29 on a connecting rod 30 which projects into a Vradial hole inpiston 23"dri1led about midway between the endsl of the latter. The connecting `rod`30 is held against movement in its socket in the piston by means of a pin 3| which is driven into registering openings in the piston and connecting rod. From this Adescription `it 2 Will be napparent that as lthe shaft 26 rotates the ball end29 of connecting rod 30 is causedvto' describe a circle. At the samev time it turns about `an aXis through its center extending longitudinally of the pumpv and also. moves inand out in the bearing provided in the plate 21 and boss 28. The connecting rod 30 is continuously changing its angle in the vertical plane 'through its axis,I thereby imparting tothe piston a continuous motion of oscillation. The piston there.- fore partakes of a compound motion, partly longitudinal and partly oscillating, with the result that any point upon the piston moves in an elliptical path.

' Twolongitudinalpassages 32 and 33 are drilled in the respective ends of the piston and extend inwardly to points somewhat short rof the middle of the piston, where they connect with radial passages or ports 34 and 35 respectively running out at the surface of the piston 'preferably in longitudinal alignment.

In the casing I6' on the side of the piston oppositethat which is engaged by the crank drive, we place a valve piece 36 which is preferably formed to t somewhat loosely in the bore of the casingand has an inner surface'which includes a cylindricalgroove or cavity 31 corresponding with the .curvature of the piston surface. This .fl .btween the piston 23 and the valve piece 36 is very accurate and smooth, the contacting surfaces being preferably ground and lapped in.

' The valve piece 36, as illustrated in Figs. 4 and 5, has four ports 38, 39, 48 and 4|, 38 and 39 being exhaust ports and the others being intake ports. As the port 34 moves in its elliptical path it registers during each stroke of the piston with valve ports 39 and 48. The piston port 35 registers with valve ports 38 and 4|. The paths of travel oi the piston ports 34 and 35 are indicated by dotted lines 34 and 35' respectively in Fig. 4. 'I'hese two paths overlap or cross each other, and the degree of overlap may be varied more or less. The greater the extent of the overlap the greater will be the length of stroke of the piston for a valve piece of given length. When this overlap is reduced to a minimum, that is when the two paths merely meet, a single intake port may be substituted for the two ports 48 and 4|, which of course simplies the valve arrangement. An example of this single intake port construction is shown in Fig. 10, to which reference will be made hereinafter.

It is desirable that there be a single intake and a single exhaust connection on the outer or rear side of the valve piece, and to this end passages are bored in the valve preferably parallel to the rear flat face thereof. The passages 42 and 43 connect the exhaust ports 38 and 39 with a rearwardly extending passage or socket 44 into which is threaded an exhaust pipe 45. Ports 48 and 4| are connected by passages 46 and 41 respectively with a rearwardly extending passage or socket `48 into which is threaded an intake pipe 49. The outer ends of the passages 42, 43, 46 and 41 are closed by threaded plugs, as indicated in Figs. 4 and 5.

In the outer side of valve piece 36 we form two or more evenly spaced sockets 58 in which we mount coil springs 5|, which bear at their opposite ends against the Valve piece 36 and the cover plate l1, thereby holding the valve piece yieldably in close contact with the moving piston 23.

When the device is used for pumping liquid the portsin the valve piece should remain open for a longer time than where it is used for handling gas. Such a valve piece is shown in Figs. 8 and 9, where the exhaust ports 58 and 59 and the intake ports 68 and 6| communicate with grooves 62, 63, 64 and 65 cut back from the curved surface of the valve piece in the paths of travel of the piston ports. In other respects the construction is like that rst described.

Fig. 10 shows the forward or inner side of a modified form of valve piece for a liquid pump, in which there are two exhaust ports 68 and 69 and a single intake port 18. Ihe exhaust ports are connected with grooves 1| and 12, while the intake port has connecting grooves 13 and 14 extending in opposite directions. The grooves 1| and 13 are arranged in the path oi the piston port 35, while the grooves 12 andY 14 are in the path of the piston port 34. The two paths in this case cross at one point only, that is at the port 18. Two passages 15 and 16 are drilled in the valve piece to connect the exhaust ports 68 and 69 with a passage or socket 11 to receive an exhaust pipe connection, but the port 18 can be connected directly to an intake pipe connection, as will be obvious.

` Operation- Referring first to the form of the invention illustrated-in Figs. 1 to 7 inclusive, and starting with the piston position illustrated in Fig. 2V, the left-hand compressor is about to start on its intake stroke and the right-hand compressor on its exhaust stroke. As soon as the piston port 34 leaves the exhaust port 39 of the valve piece suction begins to build up in the left-hand chamber, and as soon as the piston'port 35 leaves intake port 4I in the valve piece pressure begins to build up in the right-hand chamber. On this movement of the piston toward the right the ball 29 revolves in itsY circular path from the position in which it is shown in Fig. 2 down through the position indicated in Fig. '7, where the piston is located midway of the cylinder and the ports 34 and 35 are tilted up away from the line of centers of the valve ports. Movement of the ball 29 through the next quarter turn brings it up again to horizontal position and brings the ports 34 and 35 down again to horizontal position, where they register respectively with the valve, ports 48 and 38. As soon as this occurs the suction built up in the left-hand chamber draws inY avcharge of gas from the pipe 49 through the valve port 48 and passage 32. At the same time the pressure built up in the righthand chamber 'serves to expel a charge of gas from that chamber through passage 33 and port 35 to valve port 38 and through passage 42 to exhaust pipe 45. VOn the return stroke the ball 29 moves through the upper half of its circular path, and the ports 34 and 35 tilt downwardly. The reverse action then occurs, that is to say suction is built up in the right-hand chamber and pressure in the left-hand chamber, and when the piston ports again register with valve ports 39 and 4| a charge is drawn into the righthand chamber and a charge expelled from the left-hand chamber.

Such wear as occurs between the valve piece and the piston is compensated for by the springs 5I which always maintain theV valve piece in sealed relation with the piston. The possible movement of the valve piece due to this cause is of course very small indeed, but the t between the pipes 45 and 49 and the openings in plate I1 through which they extend is loose enough to permit such movement vas may occur.

The operation of the liquid pump as illustrated in Figs. 8 and 9 is much the same as in the case of the compressor, the dilerence being merely in the fact that the Valve ports are open for a greater Vlength of time, due to the grooves in the valve piece communicating with the ports. These grooves are so arranged that in spite of the crossing of the paths of the piston ports neither piston port ever communicates with a groove in the path of the other port. The intake ports are open for a short time only at the ends oi the intake strokes, and the exhaust ports are open for a longer time, in fact for about half of the exhaust stroke. Y Y

The valve piece of Fig. 10 functions in about the same way as that of Fig. 9, it being noted that the intake port remains open to each of the piston ports somewhat longer than in the case of Fig. 9, but not so long as the exhaust ports remain open. The exact timing may be determined by calculation, it being necessary to make the design such as to prevent breakage due to the inco-mpressibility of liquids.

Variations from the described structure may be employed. Accordingly we desire it to be understood that the scope of the invention is to be regarded as dened exclusively by the appended claims rather than by the foregoing description or the accompanying illustration.

Having thus described our invention, we claim:

1. In a device of the character described, a cylinder closed at one end, a piston movable in said cylinder with a compound oscillating and longitudinal motion, means for imparting said motion to the piston, said piston having a passage extending from the extremity thereof to a port in the side thereof, a valve piece formed to t the side of the piston in the vicinity of its said port, said valve piece having an intake and an exhaust port adapted to register aty proper times with the piston port as it moves in its curved path, and means for holding the valve piece against the piston to provide an effective seal.

2. In a pump, a cylinder closed at its ends, a double piston movable inV said cylinderfwith a compound oscillating and Vlongitudinal motion, means for imparting said motion to the double piston, said piston having at each end a single passage extending from the extremity of the piston to a side port near the middle thereof, the two piston ports being spaced apart, said cylinder being enlarged midway thereof, and a valve piece fitting the piston in said enlarged portion of the cylinder, said valve piece having two sets of intake and exhaust ports, the ports of each set being adapted to register at the proper times with one of said piston ports.

3. In a pump, a cylinder closed Yat its ends, a double piston movable in said cylinder with a compound oscillating and longitudinal motion, means for imparting said motion to the double piston, said piston having at each end a single passage extending from the extremity of the piston to a side port near the middle thereof, the two piston ports being spaced apart, said cylinder being enlarged midway thereof, a valve piece fitting the piston in said enlarged portion of the cylinder, said valve piece having two sets of intake and exhaust ports, the ports of each set being adapted to register at the proper times with one of said piston ports, and means for yieldably holding the valve piece against the piston.

4. In a pump, a cylinder closed at its ends, a double piston movable in said cylinder with a compound oscillating and longitudinal motion,V

means for imparting said motion to the double piston, said piston having at each end a single passage extending from the extremity of the piston to a side port near the middle thereof, the two piston ports being spaced apart, said cylinder being enlarged midway thereof, and a valve piece fitting the piston in said enlarged portion of the cylinder, said valve piece having two sets of intake and exhaust ports, the ports of each set being adapted to register at the proper times with one of said piston ports, the path of one piston port crossing the path of the other piston port.

5. In a pump, a cylinder closed at its ends, a double piston movable in said cylinder with a compound oscillating and longitudinal motion, means for imparting said motion to the double piston, said piston having at each end a single passage extending from the extremity of the piston to a side port near the middle thereof, the two piston ports being spaced apart, said cylinder being enlarged midway thereof, and a valve piece fitting the piston'in said enlarged portion of the cylinder, said valve piece having Vtwo sets of intake and exhaust ports, the ports of each set being adapted to register at the proper times with one of said piston ports, the path of one piston port crossing the path of the other piston port at two points.

6. In a device of the character described, a cylinder closed at one end, a piston free to move in said cylinder longitudinally and rotatably, said piston having a passage extending from the outer extremity of the piston to a port in the side thereof, a transversely extending cylindrical casing merging with said cylinder, a crank mounted to rotate in said casing to one side of the piston, a connecting rod mounted in the piston and joined with the crank by a universal joint, said connecting rod being adapted to change its effective length automatically as the crank revolves, whereby circular` motion imparted to the crank gives to the piston a compound motion of reciprocation and oscillation, and a valve piece formed to t the piston mounted in said casing on the side of the piston remote from said crank, said valve piece having intake and exhaust ports adapted to register at proper times with the port ofthe piston.

7. In a device of the character described, a cylinder closed at one end, a piston movable in said cylinder with a compound oscillating and longitudinal motion, means for imparting said motion to the-piston, said piston having a passage extending from the extremity thereof to a port in the side thereof, a transverse casing merging with said cylinder, a valve piece movable in the casing formed to t the piston, said valve piece having intake and exhaust ports adapted to register at proper times with the port of the piston, means for holding the valve piece against the piston, intake and exhaust pipes fixed in said valve piece, and said casing having openings for said pipes through which the pipes are free to move to a slight extent.

8. In a device of the character described, a cylinder closed at both ends, a double piston movable in said cylinder with a compound oscillating and longitudinal motion, means for imparting sai-d motion to the piston, said double piston having on either side of the center thereof a passage extending from the extremity of the piston to a port in the side thereof, a valve piece formed vwith a curved surface to fit said piston in the vicinity of its two said ports, said valve piece having intake and exhaust ports arranged to provide registration of each pisto-n port with a valve intake port and a valve exhaust port for each reciprocation of the double piston, and passages Y 

